1. Field of the Invention
The present invention relates generally to storage systems that store data.
2. Description of Related Art
Recently, the amount of power consumed by servers in some data centers is becoming a significant issue. One possible solution for this problem is server consolidation using virtual machine software. Virtual machine software is able to provide multiple virtual server environments (i.e., virtual machines or VMs) on a single server hardware (or a physical server), and thereby enable the physical single server to run multiple operating systems (OSs). What is more, virtual machines that are in operation on virtual machine software are able to be migrated to another physical server for the purpose of load balancing between physical servers, clustering in preparation for server hardware failure, and for other purposes. However, when a virtual machine is migrated from a current physical server (i.e., a source server) to another physical server (i.e., a destination server), the volumes being accessed by the virtual machine still need to be accessible from the destination server after the virtual machine has been migrated. Therefore, any volumes used by the virtual machines need to be able to be shared between the source server and the destination server, which limits flexibility of connection among physical servers and storage systems, and increases security risks.
In separate developments, multipath I/O (input/output) is a technology by which multiple paths are provided to a mass storage device in order to provide redundancy in case of failure of one of the components in one of the paths. Thus, multiple paths may be provided in an information system, such as by providing multiple ports, switches, or the like. For example, multipathing technology can enable servers to keep running in case of failure of Fibre Channel (FC) ports on a storage system or failure of links connected to the ports. Multipathing technology enables the deployment of redundant FC links between servers and storages, and the servers are able to keep running transparently without any disruption in case of the failure of a port on the storage system or links connected to the port. However, to utilize conventional multipathing technology, specialized software is required to be installed on the servers, and conventional multipathing solutions do not address the use of or failover of virtual ports.
Furthermore, disaster recovery is now a significant requirement for protecting information systems against large-scale disasters. Typically, disaster recovery is achieved by copying data from a local storage to another storage system in a remote location, often accompanied by clustering servers over networks. Although virtual machine software typically has a function to facilitate migration of a virtual machine to another server upon a failure at the first server (server clustering), virtual machine software does not meet requirements for disaster recovery because the storages still need to be shared among the servers, and the virtual machine needs to be able to access the storage volumes that it was using prior to migration, as mentioned above.
Related art includes U.S. Pat. No. 6,779,083 B2, to Ito et al., entitled “Security for Logical Unit in Storage Subsystem”, the disclosure of which is incorporated herein by reference.